Question

In pea plants, tallness (T) is dominant to shortness (t). What is the predicted genotypic ratio of the offspring if a homozygous short plant is crossed with a heterozygous tall plant? The offspring of a particular cross is 100 percent heterozygous for tallness.

Answer 1

Answer:

25% of the heterozygous cross are short, and the offspring of a homozygous dominant and homozygous recessive pea plant will always display the dominant trait (phenotype), because they are heterozygous.

Explanation:

In this explanation, I'm assuming that the allele "T" for tall plants is dominant to the allele "t" for short plants, like in Gregor Mendel's pea plant experiment.

A homozygous tall pea plant will have the genotype "TT" and a homozygous short plant will have the genotype "tt" because homozygous means that both alleles are identical. Since "T" is dominant over "t", any plant with at least one "T" allele will be tall (the dominant trait), regardless of what the other allele is. Let's look at a Punnett square for this cross:

Answer 2

25% of the heterozygous cross are short(t) and 75% are tall(T)

• The offspring of a homozygous dominant and homozygous recessive pea plant will always display the dominant trait (phenotype), because they are heterozygous.

• It is assumed that the allele "T" for tall plants is dominant to the allele "t" for short plants, like in Gregor Mendel's pea plant experiment.

• A homozygous tall pea plant will have the genotype "TT" and a homozygous short plant will have the genotype "tt" because homozygous means that both alleles are identical.
• Since "T" is dominant over "t", any plant with at least one "T" allele will be tall (the dominant trait), regardless of what the other allele is.

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